In our prior studies, naphtho[2,3-b]thiophene4,9-diones (A), 4,8-dihydrobenzo[1,2-b: 5,4-b′]dithiophene-4,8-diones(B) and, 4,8-dihydrobenzo[1,2-b: 4,5-b′]dithiophene-4,8-diones(C) were identified as potential anticancer agents [U.S. Pat. Nos. 6,174,913 B1; 6,337,346B1, details of which are incorporated herein by reference]. Among these benzothiophene analogs, many compounds possessed very potent cytotoxic activity against human tumor cell lines. However, most of these compounds were quite lipophilic, and therefore, not optimal for in vivo and clinical studies.
